(1) Field of the Invention
The present invention relates to a skin-stiffener transition assembly and to a method of manufacture of said skin-stiffener transition assembly. The present invention relates as well to applications of said skin-stiffener transition assembly.
(2) Description of Related Art
Fiber composite spars or skin-stiffener transitions are made by binding two “C” channels together to form a web with flanges. The channels may comprise a plurality of plies of fiber fabrics either in dry state or pre-impregnated with resin. When the channels are joined at the webs, an interstice or so-called interstice occurs along the flange because of these radii. Typically a gusset filler fills the interstice.
The skin-stiffener transitions are sensitive towards loads pulling off the flanges from the skin and/or sensitive towards impacts against the flanges.
The document U.S. Pat. No. 6,562,436 (A1) discloses a laminated composite (multi-ply) radius filler includes a plurality of woven fabric reinforced plies cut to fill a radius gap (including, if appropriate, intentional overfill) to increase absolute strength, to increase specific strength, or to reduce cost by reducing cracking and distortion in the radius of a composite assembly. The present invention also describes the method of manufacture and method of use for such laminated composite radius filler.
The document U.S. Ser. No. 2009/0317587 A1 discloses a composite stiffener fabricated using preforms of laminated, unidirectional composite tape. The stiffener includes a void that is reinforced by a filler wrapped with a structural adhesive. The surfaces of the preforms surrounding the void include a layer of composite fabric which is bonded to the filler by the adhesive, thereby increasing the toughness of stiffeners around the void and improving pull-off strength of the stiffener.
The document EP 0339 223 A1 discloses a fabric for making a constructional part, especially a hardened resin-saturated constructional part, the fabric consisting of an industrial yarn, such as particularly aramid fiber, carbon fiber, ceramic fiber or glass fiber, and proposes, in order to increase the proportion of reinforcing textile structure, that the fabric consists of two warp systems, of which the second serves for forming folds fastened to the first warp system at both ends, as seen in cross-section, the two warp systems being connected to one another at the fold ends by means of fixing wefts. The textile structure can advantageously be produced in one piece; there is no need for a multi-part construction making it more expensive.
The document U.S. Pat. No. 4,909,655 A discloses a joint for aircraft wing skins which have previously been connected to support substructures by rivets or other mechanical fasteners which create stress points and leakage points when aircraft wings are filled with fuel. Interleaved plies of a composite fabric are used to mechanically interlock the wing skin and support substructure. The structural integrity of the connection joint between wing skin and support substructure is increased.
The document U.S. Pat. No. 3,185,605 A discloses laminates of glass cloth, felted fibers, knitted cloth, parallel threads or paper, bonded with cold-setting or thermosetting resin made with selected areas left unbonded by interleaving the layers in those areas, or parts thereof adjacent to the areas to be bonded, with sheets, e.g. of polyvinyl chloride or polythene, incompatible with the resin and holding them under pressure during impregnation of the layers with, and curing of, the resin. The unbonded layers may later be interleaved or otherwise combined with the layers of other laminates to make shaped articles.